Extrusion die and method for making the same

ABSTRACT

Rod-extruding die has toughness gradient increasing from the throat end to entrance end, and hardness or compressive strength gradient increasing from entrance end to throat end. Die may be cut (1) from non-uniformly work-hardened billet, (2) from nonuniformly-quenched heat-treatable billet, (3) from sintered billet produced by cofiring plural layers of sinterable powders having different post-sintering characteristics of toughness and hardness and arranged to provide toughness and hardness gradient in billet, (4) from billet produced by brazing plural elements having different characteristics of toughness and hardness and arranged to provide toughness and hardness gradient in billet. Die may also be formed by molding and compacting plural layers of sinterable powder material having different post-sintering toughness and compressive strength characteristics, in the form of the die, and cosintering to produce the die, the layers being arranged to provide a toughness and a hardness gradient in the die.

United States Patent Fuchs, Jr. et al.

[ Feb. 26, 1974 EXTRUSION DIE AND METHOD FOR MAKING THE SAME [75]Inventors: Francis Joseph Fuchs, Jr.;

Peruvemba Swaminatha Venkatesan, both of Princeton, NJ.

[73] Assignee: Western Electric Company Incorporated, New York, NY.

[22] Filed: Oct. 2, 1972 [21] Appl. No.: 293,886

' Related US. Application Data [62] Division of Ser. No. 150,496, June7, 1971.

[52] US. Cl 76/107 R [51] Int. Cl B2lk 5/20 [58] Field of Search 76/107R, 107 A, 107 AS [56] References Cited UNITED STATES PATENTS 2,058,] 10l0/l936 Schroter et a1. 76/107 A 2,066,372 l/l937 Tomalis 76/107 R1,784,866 l2/l930 Fahrenwald.... 76/107 R 1,992,905 Wills 76/l07 RPrimary Examiner-Harrison L. Hinson Attorney, Agent, or Firm-JackSchuman 5 7 ABSTRACT Rod-extruding die has toughness gradient increasingfrom the throat end to entrance end, and hardness or compressivestrength gradient increasing from entrance end to throat end. Die may becut (I) from non-uniformly work-hardened billet, (2) fromnonuniformly-quenched heat-treatable billet, (3) from sintered billetproduced by cofiring plural layers of sinterable powders havingdifferent post-sintering characteristics of toughness and hardness andarranged to provide toughness and hardness gradient in billet, (4) frombillet produced by brazing plural elements having differentcharacteristics of toughness and hardness and arranged to providetoughness and hardness gradient in billet. Die may also be formed bymolding and compacting plural layers of sinterable powder materialhaving different post-sintering toughness and compressive strengthcharacteristics, in the form of the die, and cosintering to produce thedie, the layers being arranged to provide a toughness and a hardnessgradient in the die.

5 Claims, 7 Drawing Figures ROCKWELL c" HARDNESS Pmmen z 7 3,793.91 1

I saw 1 BF 2 HARDNESS ROCKWELL C HARDNESS TOUGHNESS ROCKWELL c" HARDNESSEXTRUSION DIE AND METHOD FOR MAKING THE SAME.

This is a division of application Ser. No. 150,496 filed June 7, 1971.

BACKGROUND OF THE INVENTION 1. Field of the Invention This inventionrelates to an improved extrusion die and to methods for making the same.

2. Description of the Prior Art Extrusion dies used, for example, in thehydrostatic extrusion of rod to produce wire, conventionally embody agenerally physically homogeneous structure, no provision being made toprovide the die with a profile of physical properties (compressivestrength to hardness, toughness or ductility) tailored to meet theparticular stresses imposed upon various portions of the die.

Consequently, such extrusion dies represent a compromise in design andare not entirely satisfactorily in operation, or the dies areoverdesigned, and hence expensive, in order to provide satisfactoryoperating characteristics.

The present invention provides an extrusion die having high compressivestrength or hardness at the throat end and a high degree of toughness atthe entrance end. The present invention also provides novel methods ofmaking such an improved extension die, whereby to overcome deficienciesnoted in conventional extrusion dies.

SUMMARY OF THE INVENTION One of the objects of this invention is toprovide an improved extrusion die.

Another of the objects of this invention is to provide novel methods formaking an improved extrusion die.

Still another object of this invention is to provide an improvedextrusion die of particular utility and efficiency in continuoushydrostatic extrusion of rod to produce wire.

Yet a further object of this invention is to provide an extrusion die inwhich, in a broad sense, hardness and toughness vary longitudinally inthe die body between the entrance end and the throat end, i.e., the diehas a toughness gradient increasing toward the entrance end and ahardness gradient increasing toward the throat end.

Another object of this invention is to provide an improved extrusion diehaving a profile of physical properties (e.g., toughness, hardness)tailored to meet particular stresses imposed upon various portions ofthe die.

Yet a further object of this invention is to provide an improvedextrusion die having high compressive strength'or hardness at the throatend of the die, and having a large degree of toughness at the entranceend of the die.

Still other and further objects of this invention will become apparentduring the course of the following description and by reference to theaccompanying drawings and the appended claims.

Briefly, we have discovered that the foregoing objects may be attainedby forming an extrusion die from a billet of material having toughnessincreasing from one end to the other and hardness increasing in theopposite direction so that the die, when formed, has greatest toughnessat the entrance end thereof and greatest hardness at the throat endthereof.

BRIEF DESCRIPTION OF THE DRAWINGS Referring now to the drawings in whichlike numerals represent like parts in the several views:

FIG. 1 represents a medial longitudinal section of a representativeapparatus for hydrostatic extrusion, showing a rod being extrudedthrough a conventional die to produce wire.

FIG. 2 represents a medial longitudinal section through the improved dieof the present invention, the distribution of toughness and hardness(i.e., the toughness gradient and the hardness gradient) along the diebeing indicated diagrammatically to one side of the die, and anillustrative distribution of hardness values likewise being indicateddiagrammatically to one side of the die.

FIG. 3 represents diagrammatically a view of a conical billet of workhardenable material, shown in solid lines, being subjected to forces ofcompression, shown by the arrows, and strained to produce a rectangularbillet, shown in phantom outline, an illustrative distribution ofhardness values in the thus-non-uniformly worked rectangular billetbeing indicated diagrammatically, the die to be produced from therectangular billet and its orientation with respect thereto being indicated in dotted outline, said die corresponding with the die shown inFIG. 2.

FIG. 4 represents diagrammatically a view of a billet of heat treatablematerial being end-quenched to achieve a distribution of hardness valuesindicated by way of illustration in the figure, the die to be producedfrom the end-quenched billet and its orientation with respect theretobeing indicated in dotted outline, said die corresponding with the dieshown in FIG. 2.

FIG. 5 represents diagrammatically a view of a billet of cosinteredpowder materials of different postsintering hardness and toughnesscharacteristics having a distribution of hardness values as shownillustratively in the figure, the die to be produced from the sinteredbillet and its orientation with respect thereto being indicated indotted outline, said die corresponding with the die shown in FIG. 2.

FIG. 6 represents diagrammatically a view of a billet of elements havingdifferent hardness and toughness characteristics secured, as by brazing,to each other, a distribution of hardness values being shownillustratively in the figure, the die to be produced from the compositebillet and its orientation with respect thereto being indicated indotted outline, said die corresponding with the die shown in FIG. 2.

FIG. 7 represents a vertical medial section of molds forming andcompacting layers of cosinterable powder 7 materials of differentpost-sintering hardness and toughness characteristics in the form of thedie shown in FIG. 2.

DESCRIPTION OF THE PREFERRED EMBODIMENTS Representative apparatus forthe hydrostatic extrusion of rod 1 to produce wire 2 is shown in FIG. 1as comprising chamber 3 receiving the said rod 1 and conventionalextrusion die 4 supported within the chamber 3 by means of die stem 5,the latter being provided with a longitudinal aperture 6 through whichthe extruded wire 2 passes. It will be understood that the effect ofextrusion shock is greatest at the entrance end of the die, andlongitudinal compression forces are at a maximum at the throat end ofthe die. Die 4 generally has uniform values of hardness and toughnesslongitudinally thereof, and therefore die 4 is either inadequatelydesigned to resist extrusion shock which, as above mentioned, isgreatest at the die entrance end, or is overdesigned to resist thelongitudinal compression forces which are a maximum atthe throat end ofthe die.

An improved extrusion die 7 is shown in FIG. 2. Die 7 is provided with alongitudinal toughness gradient and a longitudinal hardness gradient asindicated diagrammatically. Specifically, die 7 has the greatesttoughness at the entrance end thereto, which toughness decreases towardthe throat end of die 7. Conversely, die 7 has the greatest hardness orcompressive strength at the throat end of the die which hardness orcompressive strength decreases toward the entrance end thereof. Morespecifically, Rockwell C values 'of hardness are shown as rangingbetween a lower value of 50 at the entrance end to die 7 and an uppervalue of 65 at the throat end of die 7. it will be understood that theseRockwell C values of hardness are merely illustrative.

FIG. 3 illustrates one method of making die 7. A conical billet 6 ofwork-hardenable material (e.g., a workhardenable steel) is deformed, bycompressive forces 9, to the cylindrically shaped billet shown inphantom lines, the material adjacent the upper surface of billet 10having been strained and therefore work-hardened to a greater degreethan the material adjacent the lower surface of billet 10, and thematerial between the upper and lower surfaces of billet 10 having beenstrained and therefore work-hardened to an intermediate degree. It willbe seen, therefore, that because of the progressively greater working ofthe material of billet 10 from the bottom to the upper surface thereof,the hardness of billet 10 will increase from the bottom to theuppersurface thereof, as indicated in the scale of Rockwell C hardness valuesshown in the figure (which values are illustrative only). It will, ofcourse, be understood that the initial hardness of the materialconstituting billet 8, and the configuration of billet 8 relative tobillet 10, will be so chosen as to produce a-billet 10 having thedesired range of Rockwell C values.

After billet 10 with the said desired range of Rockwell C values hasbeen produced by the method hereinbefore described, die 7 can be cutfrom billet 10 as shown.

FIG. 4 illustrates another method of making die 7. A billet ll ofheat-treatable material (e.g., heat treatable steel), after having beenelevated to the proper prequenching temperature for heat treating, isquenched at one end only. The effect of this end quenching will begreatest at the top surface of billet 11 and will decrease toward thebottom surface of billet 11. It will be seen therefore that the hardnessof billet 11 will decrease from the top surface of billet 11 toward thebottom surface thereof, as indicated on the scale of Rockwell C hardnessvalues shown in the figure (which values are illustrative only).

After billet 11 with the desired range of Rockwell C" values has beenproduced by the end-quenching method hereinabove described, die 7 can becut from billet 11 as shown.

FIG. 5 illustrates yet another method of making die 7. A plurality oflayers 12 of compatible sinterable powder materials having differentpost-sintering characteristics of hardness and toughness is arranged sothat, after firing and cosintering the said' layers 12, a compositebillet 13 is produced having toughness increasing from one end to theother and hardness increasing in the opposite direction, as indicated onthe scale of Rockwell C hardness values (which values are illustrativeonly).

After composite billet 13 with the desired range of Rockwell C hardnessvalues has been produced, die 7 can be cut from composite billet 13 asshown.

FIG. 6 illustrates still another method of making die 7. A plurality ofelements 14 of varying toughness and hardness is arranged and assembled,and the elements 14 brazed to each other to form a composite billet 15having toughness increasing from one end to the other and hardnessincreasing in the opposite direction, as indicated on the scale ofRockwell C hardness values (which values are illustrative only).

After composite billet 15 with the desired range of Rockwell C hardnessvalues has been produced, die 7 can be cut from composite billet 15 asshown.

FIG. 7 illustrates another method of making a die 7 I of cosinteredpowder materials, and is an alternate to the method demonstrated in FIG.5. Mold l6,'having a profile corresponding with the inner surface of die7, i.e., the surface converging from the entrance to the throat of thedie 7 and the land through the die throat, is placed in barrel l7, andlayers 18 of sinterable powder materials having different post-sinteringcharacteristics of toughness and hardness are formed in barrel 17 overmold 16, the said layers 18 being so arranged that, after mold 19 isintroduced into barrel l7 and forced downwardly to mold and compact thesaid powder materials, and after the molded and compacted powdermaterials have been removed from barrel 17 and tired to cosinter thesame, die 7 resulting from the firing operation will have toughnessincreasing from the throat to the entrance thereof and hardnessincreasing in the opposite direction, with the desired range of hardnessvalues shown for illustrative purposes in the other figures.

What is claimed is:

1. Method of making a die having an entrance end adapted to receive aworkpiece and a throat end downstream of said entrance end, said methodcomprising:

a. applying force to a billet of work-hardenable material todifferentially change the cross-sectional area of said billet from oneend thereof toward an opposite end thereof thereby differentiallydeforming said billet to produce a deformed billet having apredetermined hardness gradient increasing from said one end toward saidopposite end of said deformed billet,

b. forming a die from said deformed billet with the entrance end to thedie formed from that portion of said deformed billet having lowerhardness and the throat end of the die formed from that portion of saiddeformed billet having greater hardness.

2. Method of making a die having an entrance end adapted to receive aworkpiece and a throat end downstream of said entrance end, said methodcomprising:

a. forming a conical billet of work-hardenable material with apredetermined profile;

b. applying force to opposite ends of said conical billet parallel tothe altitude thereof sufficient to compress and deform said billet,thereby to foreshorten d. step (a) is performed by forming a truncatedconical billet.

4. Method as in claim 2, wherein:

e. step (b) is performed by deforming said conical billet to arectangular shape.

5. Method as in claim 2, wherein:

d. performing step (c) by forming said die with its longitudinal axisregistering with the original altitude of the billet.

L-566-PT UNITED STATES PATENT OFFICE CERTIFICATE OF CORRECTION'PatenrNo. 3,793,911 I Dated February 97M Inventor-FRANCIS JOSEPH FUCHS,J'R.; PERUVEMBA SWAMINATHA VENKATESAN It is certified that error appearsin the above-identified parent and that said Letters Patent are herebycorrected as shown below:

IN THE SPECIFICATION: I

Column 1, line 16, "to" should read --or--; line 20 "satisfactorilyshould read "satisfactory"; line 28 "extension" should read --extrusion.

Column 3, line 26, billet 6" should read billet 8--.

Signed and sealed this 11th day of June 197L|.. v

(SEAL) Attest:

EDWARD M.FLETCHER,JR. Attesting Officer C. MARSHALL DANN Commissioner ofPatents

1. Method of making a die having an entrance end adapted to receive aworkpiece and a throat end downstream of said entrance end, said methodcomprising: a. applying force to a billet of work-hardenable material todifferentially change the cross-sectional area of said billet from oneend thereof toward an opposite end thereof thereby differentiallydeforming said billet to produce a deformed billet having apredetermined hardness gradient increasing from said one end toward saidopposite end of said deformed billet, b. forming a die from saiddeformed billet with the entrance end to the die formed from thatportion of said deformed billet having lower hardness and the throat endof the die formed from that portion of said deformed billet havinggreater hardness.
 2. Method of making a die having an entrance endadapted to receive a workpiece and a throat end downstream of saidentrance end, said method comprising: a. forming a conical billet ofwork-hardenable material with a predetermined profile; b. applying forceto opposite ends of said conical billet parallel to the altitude thereofsufficient to compress and deform said billet, thereby to foreshortenthe altitude of said billet and to differentially increase thetransverse cross-sectional area to a predetermined degree, whereby todifferentially work-harden the billet in a direction parallel to thealtitude thereof; c. forming said die from said billet, the longitudinalaxis of said die being parallel to the altitude of said billet, theentrance end to said die facing the base of said billet.
 3. Method as inclaim 2, wherein: d. step (a) is performed by forming a truncatedconical billet.
 4. Method as in claim 2, wherein: e. step (b) isperformed by deforming said conical billet to a rectangular shape. 5.Method as in claim 2, wherein: d. performing step (c) by forming saiddie with its longitudinal axis registering with the original altitude ofthe billet.